2 The Lymphatic System System of tissues and vessels Scattered throughout the bodyServices almost all regions
3 Functions of the Lymphatic System Fluid balanceLymph fluidProtection from infectionAbsorption of fats
4 lymphatic system in relation to the cardiovascular system Lymphatic vessels pick up fluid in the tissues and return it to the blood in vessels near the heart. Zooming In: What type of blood vessel receives lymph collected from the body?
5 Lymphatic Circulation One-way systemBegins in tissuesEnds in bloodstream
6 Lymphatic Capillaries Capillary walls (endothelium) are flattened epithelial cellsMore permeable than blood capillariesOverlapping cells form one-way valvesArise blindly (closed at one end)Lacteals absorb digested fats
7 Lymphatic Vessels Superficial sets Deep sets Nodes Right lymphatic ductThoracic duct (left lymphatic duct)Cisterna chyli
8 Lymph Vessels and Lymph Nodes Lymph nodes and vessels of the head.Drainage of right lymphatic duct and thoracic duct into subclavian veins.
9 Movement of LymphSegments of vessels located between the valves contract rhythmicallySkeletal muscles compress vessels
10 Lymphoid Tissue Distributed throughout the body Makes up specialized organs of lymphatic system
12 Structure of a lymph node Arrows indicate the flow of lymph through the node.Section of a lymph node as seen under the microscope (low power).Zooming In: What type of lymphatic vessel carries lymph into a node? What type of lymphatic vessel carries lymph out of a node?
13 The Spleen Cleanses blood Destroys old red blood cells FiltrationPhagocytosisDestroys old red blood cellsProduces red blood cells before birthIs reservoir for blood
14 The Thymus Plays key role in early immune system development Produces thymosinDevelops T lymphocyte cellsPromotes lymphocyte growthPromotes lymphoid tissue activityShrinks after puberty
15 The Tonsils Remove contaminants and trap pathogens Palatine tonsils Pharyngeal tonsil (adenoids)Lingual tonsilsSurgery to treat if recurrent infection or enlarged tonsils make swallowing/breathing difficult